1. Field of the Invention
This invention relates to a method and system for visualizing and characterising fluids flowing in a means defining a fluid flow path.
2. Related Art
Pulsed Ultrasound Velocimetry (PUV) is a technique for measuring an instantaneous velocity profile in liquid flow along a pulsed ultrasonic beam axis. The instantaneous velocity profile is obtained by detecting the relative time lags of backscattered ultrasound echoes from moving particles between successive pulse emissions. As shown in the article by D. W. Baker, ‘Pulsed Ultrasonic Doppler Blood-Flow Sensing’, IEEE Transactions on Sonics and Ultrasonics, vol. SU-17, No. 3, July 1970, hereby incorporated by reference, ultrasonic signals may be used for non-invasive measurements of fluid velocities.
It would be desirable to adapt such techniques to provide a method for fluid flow metering, visualization and rheological characterisation.
Commercially available ultrasonic flow meters are based on either transit-time or pulsed Doppler methods. It would be desirable to use a combination of transit-time and pulsed ultrasound methods to improve volumetric flow rate measurements and thereby also improve the accuracy of in-line rheometry.
Methods for in-line rheometry are often based on traditional tube viscometry concepts where shear rates are obtained from measurements of the volumetric flow rate in the pipes, and the shear stresses at inner pipe walls are determined from simultaneous measurements of pressure difference over fixed distances along the pipe.
The UVP technique with Pressure Difference (PD) measurements, usually referred to as the UVP+PD methodology, is used to characterise fluids flowing in fluid flow paths, e.g., in pipes.
The UVP+PD methodology has been applied to a wide range of fluid systems, including a range of model and industrial fluids and suspensions, containing both soft and hard particles and fibres with diameters from a few nanometers up to several centimeters in length. It has also been evaluated for several potential industrial applications, such as polymer melt rheology, paper pulp, concentrated mineral suspensions, and fat crystallisation.
However, no commercial UVP+PD system is readily available on the market and systems used until now have been typically based on off-the-shelf transducers and electronics and are therefore more suited for simple flow characterisation with limited accuracy without meeting industrial requirements.
Also, conventional UVP+PD instruments typically used in research environments, systems/instrumentation and methodologies do not possess robustness and accuracy required in industrial applications. One problem is that conventional off-the-shelf type transducers and instrumentation used in UVP (and UVP+PD) systems are not designed for measurements inside small and complex geometries, such as industrial processing pipes. Also, conventional UVP instruments have been adapted from simplified designs and methodologies found in the medical industry for measurement of blood flow. However, human blood, and also water, is not attenuating compared to current industrial fluid systems and thus the existing UVP instruments are not able to provide desired functionality to the latter.
It is therefore an object of the present invention to at least address the above-mentioned problems and issues.